Alkali metal carbonates and sodium carbonate in particular are very widespread industrial products with many applications. In the glass industry, sodium carbonate is an essential ingredient for easier processing of the glass.
The detergent, textiles, pulp and paper industries are also examples of industries consuming a large quantity of sodium carbonate.
Due to this extremely high consumption, methods for producing sodium carbonate are of great economic and environmental importance.
Sodium carbonate can be obtained by purifying natural sodium carbonate extracted from trona deposits or by synthesis. Most synthetic sodium carbonate is currently produced by the “SOLVAY” process also called the ammonia process. In this process, ammonia is absorbed by a sodium chloride solution. The ammoniacal brine thus formed is contacted with carbon dioxide to produce bicarbonate, which is separated from the mother liquor and then calcined. The ammonia present in the mother liquor and the carbon dioxide liberated during calcination are recovered and recycled.
However, this process requires extremely high investments.
In patent BE861527 of the applicant, another method is described, in which an aqueous sodium chloride solution is electrolyzed in a cell with a membrane selectively permeable to the ions in order to produce chlorine and an aqueous sodium hydroxide solution which is carbonated and then evaporated to produce sodium carbonate crystals. In this method, the carbonation is carried out by mixing the sodium hydroxide with a bicarbonated solution in the electrolyzer. However, an efficient carbonation by liquid mixing has proved difficult to achieve.